(1) Field of the Invention
The present invention relates to a synthetic resin shaped article having good and permanent antistatic properties, and a process for the preparation thereof.
(2) Description of the Related Art
Currently, the many synthetic resin shaped articles available have excellent properties, but in general, since they have a high electric resistance value, they are easily electrically charged by friction or the like and attract dust and foreign matter to thereby mar the appearance thereof.
As methods of imparting antistatic properties to synthetic resin shaped articles, there can be mentioned (1) an internal addition of a surface active agent, (2) a surface coating of a surface active agent, (3) a surface coating of a silicon compound, and (4) a surface modification by a plasma treatment. Among these methods, the methods (3) and (4) are disadvantageous in that the cost thereof is high, and therefore, the methods (1) and (2) are generally adopted.
In the method of an internal addition of a surface active agent, the surface active agent is incorporated or dispersed in a starting material for a synthetic resin before the polymerization, or in a synthetic resin before the molding, and therefore the preparation process can be simplified. But to obtain satisfactory antistatic properties, usually the amount added of the surface active agent added must be increased, which can result in a lowering of the mechanical strength of the synthetic resin. Further, the obtained antistatic characteristics are easily lost by water washing, friction or the like.
The method of surface coating a surface active agent is advantageous in that the physical properties of a synthetic resin as the substrate are not affected and good antistatic properties can be obtained by using a small amount of the surface active agent. Nevertheless, since the surface coating step is necessary, the cost is increased and there is a risk of a marring of an inherent aesthetically pleasing surface of the synthetic resin shaped article. Furthermore, the obtained antistatic properties are easily lost by water washing, friction or the like.
As apparent from the foregoing description, a synthetic resin shaped article having good and permanent properties while retaining the inherent physical properties of the synthetic resin has not been developed.